Image capturing device and method thereof

ABSTRACT

An image capturing device is provided comprising an image sensor for capturing a first image of a scene, a light source for illuminating the scene with a first flash of coded light, and a network interface for communicating with a communications network and/or a further image capturing device. The device is operative to encode information into the first flash, enabling retrieval of the first image from a first data storage, capture the first image, and store the first image in the first data storage. Optionally, the device may be operative to detect a second flash of coded light emitted by the further image capturing device, decode information enabling retrieval of a second image captured by the further image capturing device from a second data storage, retrieve the second image, and create a 3D model from the first image and the second image.

TECHNICAL FIELD

The invention relates to an image capturing device, a method of an imagecapturing device, a corresponding computer program, and a correspondingcomputer program product.

BACKGROUND

Numerous algorithms are available for creating a three-dimensional (3D)model from a set of two-dimensional (2D) images, with each 2D imagebeing taken from a different angle relative to the captured scene (see,e.g., T. Moons, L. Van Gool, and M. Vergauwen, “3D Reconstruction fromMultiple Images Part 1: Principles”, Foundations and Trends in ComputerGraphics and Vision, Vol. 4, pages 287-404, 2010; and J. Li, E. Li, Y.Chen, L. Xu, “Visual 3D Modeling from Images and Videos”, Technicalreport, Intel Labs China, 2010). In simple terms, such algorithmsperform the reverse process of obtaining 2D images from a 3D model. Forinstance, “123D Catch” is an iPad app by Autodesk which makes itpossible to turn pictures into a 3D model [see, e.g.,http://www.123dapp.com/catch].

The 3D model can subsequently be used for rendering images, such as 2Dimages for arbitrary viewing directions, or images which achieve astereoscopic 3D effect by encoding each eye's image using filters ofdifferent, usually chromatically opposite colours, typically red andcyan (known in the art as ‘anaglyph 3D’).

The extent to which a 3D scene can be recreated depends on the numberand spatial relation of the 2D images used. If the scene is captured in2D images from a wider range of view-points, the 3D effect can beextended to a greater angle.

Even though algorithms for creating a 3D model from a set of 2D imagesexist, their use remains a niche activity as it often requiresspecialist equipment and/or extensive preparation. Creation of 3D modelsis particularly problematic when the scene is dynamic rather thanstatic, e.g., where the scene contains a person. In such case, a set of2D images needs to be captured from different angles relative to thescene within a relatively short time interval, requiring use ofsynchronized cameras.

A potentially attractive scenario is where a group of people, e.g.,guests at a wedding, a birthday party, or the like, hereinafter alsoreferred to as participants, each captures one 2D image, and theseimages are collated and used to create a 3D model of the captured scene.

There are two obstacles which hamper a quick and simple recreation of a,possibly non-static, 3D scene. Firstly, the 2D images need to either beselected after they have been captured, or their capturing needs to becoordinated, so that their respective time of capture occurs atapproximately the same time, i.e., within a relatively short timeinterval. This requires accurate time synchronisation or triggeringbetween different cameras, or capturing of a large number of images andselecting images which are appropriate for reconstructing a 3D modelfrom the set of captured images.

Secondly, the selected images need to be transferred/exchanged betweenthe participants' devices, which may be an issue where the participantsdo not know each other, do not wish to exchange contact information tofacilitate sharing of images, or are not willing to spend time ‘pairing’their camera with the cameras of other participants. For mostsituations, the level of coordination and networking of cameras which isrequired for creating a 3D model from a set of 2D images is overlycomplicated.

SUMMARY

It is an object of the invention to provide an improved alternative tothe above techniques and prior art.

More specifically, it is an object of the invention to provide animproved solution for sharing images. It is a further object of theinvention to provide an improved solution for creating a 3D model from aset of 2D images.

These and other objects of the invention are achieved by means ofdifferent aspects of the invention, as defined by the independentclaims. Embodiments of the invention are characterized by the dependentclaims.

According to a first aspect of the invention, an image capturing device,such as a mobile terminal, a smartphone, a User Equipment (UE), atablet, or a digital camera, is provided. The image capturing devicecomprises an image sensor for capturing a first image of a scene, alight source for illuminating the scene with a first flash of codedlight during capturing of the first image by the image sensor, and anetwork interface for effecting wireless communications with acommunications network and/or a further image capturing device. Theimage capturing device further comprises processing means which areoperative to encode information into the first flash. The informationwhich is encoded into the first flash enables retrieval of the firstimage from a first data storage. The processing means are furtheroperative to capture the first image, and store the first image in thefirst data storage.

According to a second aspect of the invention, a method of an imagecapturing device, such as a mobile terminal, a smartphone, a UE, atablet, or a digital camera, is provided. The method comprisesilluminating a scene with a first flash of coded light, whereininformation is encoded into the first flash. The method furthercomprises capturing a first image of the scene and storing the firstimage in a first data storage. The information which is encoded into thefirst flash enables retrieval of the first image from the first datastorage.

According to a third aspect of the invention, a computer program isprovided. The computer program comprises computer-executableinstructions for causing a device to perform the method according to anembodiment of the second aspect of the invention, when thecomputer-executable instructions are executed on a processing unitcomprised in the device.

According to a fourth aspect of the invention, a computer programproduct is provided. The computer program product comprises acomputer-readable storage medium which has the computer programaccording to the third aspect of the invention embodied therein.

The invention makes use of an understanding that the process of creatinga 3D model from a set of 2D images, which are individually captured bydifferent cameras or other image capturing devices operated byindividuals of a group of people, may be improved by utilizing flashesof coded light which carry information about where and/or how an imagetaken by the image capturing device emitting the flash can be retrieved.For instance, the encoded information may comprise a location of theimage in a data storage, such as an Internet Protocol (IP) address or aUniform Resource Locator (URL), any other type of network address, or adevice identifier, and/or credentials which are required for retrievingthe image from the data storage, such as a login and/or a password, or ashared secret. The data storage may be comprised in the image capturingdevice, such as a built-in memory or a memory card. Alternatively, thedata storage may be an external data storage which is accessible over acommunications network, such as a server or a network node on theInternet which may be operated by a social network provider likeFacebook or Instagram.

To this end, if a user takes an image with his/her image capturingdevice, e.g., a smartphone or a mobile terminal comprising a camera, ora digital camera, the scene is being illuminated with coded lightemitted by the flash of the image capturing device. The coded lightcontains information about where and/or how the image can be accessed.This information can be encoded either spatially or temporally, and theencoding can be achieved through the variation of a number ofparameters, such as brightness or color balance. Even in cases wherevisible light is used, which is the case for most camera flashes,information can be encoded in a way which is imperceptible to the humaneye. This technology is known as Visible Light Communication (VLC).

According to an embodiment of the invention, the image sensor isoperative to detect a second flash of coded light emitted by a furtherimage capturing device and the processing means are further operative todecode information which is encoded into the second flash. The encodedinformation enables retrieval of a second image captured by the furtherimage capturing device from a second data storage. For instance, theencoded information may comprise a location of the second image in thesecond data storage, such as an IP address or a URL, any other type ofnetwork address, or a device identifier, and/or credentials which arerequired for retrieving the image from the second data storage, such asa login and/or a password, or a shared secret. The second data storagemay either be comprised in the further image capturing device, or may bean external data storage which is accessible over a communicationsnetwork, such as a server or a network node on the Internet. Theprocessing means are further operative to retrieve the second image fromthe second data storage, which may be the same as the first data storageor separate from the first data storage, and create a 3D model from thefirst image and the second image. Optionally, the 3D model is onlycreated if a time interval between capturing the first image andcapturing the second image is below a threshold time interval, i.e.,only if it is assessed that the second image is suitable for creating a3D model from the first image and the second image. If a dynamic sceneis captured, the threshold time interval may be determined based on anamount of motion in the scene. That is, the faster the scene changes,the shorter the threshold time interval. Further optionally, the secondimage is only retrieved if the time interval is below the threshold timeinterval. There may be other criteria which are used in addition to, orinstead of, the time interval which has passed between capturing thefirst image and capturing the second image in assessing whether thefirst image and the second image are suitable for creating a 3D model.For instance, the suitability of the second image for creating a 3Dmodel may be assessed based on the brightness of the second image. Ifthe second image is sufficiently bright, this is an indication that thesecond image has captured the scene which was illuminated by the firstflash.

The use of a flash emitting coded light not only allows information tobe exchanged between digital cameras, smartphones, or other imagecapturing devices, without any manual pairing or exchange of personalinformation. Rather, by detecting a flash emitted by another imagecapturing device, the time of capture of the image just captured by theother image capturing device is known to the image capturing devicedetecting the flash. This is the case since a flash emitted by an imagecapturing device coincides with the capture of an image by that device.Finally, detecting a flash is an assurance that the image taken by theother image capturing device is of substantially the same scene as thatbeing viewed by the image capturing device detecting the flash. This isthe case since light emitted by a camera flash has a limited range,typically up to a few or maybe ten meters. Hence, the fact the imagecapturing device has detected the flash of the other image capturingdevice is an indication that it was in proximity of the other imagecapturing device, with the field of view of its image sensor beingdirected towards the scene which was illuminated by the flash of theother image capturing device.

Thus, if a flash of coded light is detected by the image capturingdevice, the image capturing device can decode the information containedin the flash, assess the suitability of the image for use in thecreation of a 3D model, and obtain a copy of the image if the image isassessed to be suitable for creating a 3D model. The copy of the imagecan be obtained by utilizing the information retrieved from the flash.After two or more 2D images of a scene are obtained, each taken within asufficiently short time interval and from a different angle relative tothe scene, they can be algorithmically combined to create a 3D model ofthe captured scene, using one of the algorithms known in the art.

Alternatively, rather than retrieving the second image from the seconddata storage, the processing means may further be operative toassociatively store the decoded information with the first image. Thismay be achieved by storing the decoded information with the first image,e.g., as metadata. As an alternative, the decoded information may bestored in a database together with information identifying the firstimage, e.g., a filename or an identifier of the first image. Theassociatively stored information can subsequently be used for creating a3D model from a set of 2D images, by retrieving one or more 2D imagesusing the associatively stored information and algorithmically combiningthe 2D images into a 3D model using one of the algorithms known in theart.

According to an embodiment of the invention, the first image may becaptured in response to detecting the second flash emitted by thefurther image capturing device. That is, rather than capturing an imageindependently of other image capturing devices, and assessing thesuitability of images captured by other image capturing devices based ontheir respective time of capture, capturing the first image may betriggered by detecting a flash which is emitted by another imagecapturing device. Thereby, the first image and the second image arecaptured within a relatively short time interval, which makes it likelythat the first image and the second image are suitable for creating a 3Dmodel. In a scenario where several image capturing devices are used forcapturing images of a scene, a set of 2D images which are capturedwithin a relatively short time interval may be obtained using the flashof the first image capturing device taking a picture of the scene fortriggering the other image capturing devices.

Even though advantages of the invention have in some cases beendescribed with reference to embodiments of the first aspect of theinvention, corresponding reasoning applies to embodiments of otheraspects of the invention.

Further objectives of, features of, and advantages with, the inventionwill become apparent when studying the following detailed disclosure,the drawings and the appended claims. Those skilled in the art realizethat different features of the invention can be combined to createembodiments other than those described in the following.

BRIEF DESCRIPTION OF THE DRAWINGS

The above, as well as additional objects, features and advantages of theinvention, will be better understood through the following illustrativeand non-limiting detailed description of embodiments of the invention,with reference to the appended drawings, in which:

FIG. 1 illustrates a group of image capturing devices capturing imagesof a scene, in accordance with an embodiment of the invention.

FIG. 2 shows a smartphone and a digital camera, in accordance withembodiments of the invention.

FIG. 3 shows sequence diagrams illustrating embodiments of the inventionwhich utilize an internal data storage.

FIG. 4 shows a sequence diagram illustrating embodiments of theinvention which utilize an external data storage.

FIG. 5 shows embodiments of the processing unit of the image capturingdevice.

FIG. 6 is a flow chart illustrating a method of an image capturingdevice, in accordance with embodiments of the invention.

All the figures are schematic, not necessarily to scale, and generallyonly show parts which are necessary in order to elucidate the invention,wherein other parts may be omitted or merely suggested.

DETAILED DESCRIPTION

The invention will now be described more fully herein after withreference to the accompanying drawings, in which certain embodiments ofthe invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided byway of example so that this disclosure will be thorough and complete,and will fully convey the scope of the invention to those skilled in theart.

FIG. 1 illustrates a group of people 121-123, such as guests at awedding, each using a respective image capturing device 131-133 forcapturing a 2D image of a scene 110. Each of image capturing devices131-133 is an electronic device capable of capturing an image, commonlyreferred to as taking a picture, with a respective field of view141-143. Image capturing devices 131-133 may be embodied as smartphones210 or digital cameras 220 shown in FIG. 2, mobile terminals, UEs,tablets, or the like.

In the following, embodiments of the invention are elucidated withreference to FIGS. 3 and 4, which exemplify the interaction between twoof image capturing devices 131-133, first image capturing device 131 andsecond image capturing device 133, by way of sequence diagrams.

Sequence diagram 310 illustrates embodiments of the invention whichutilize an internal data storage, i.e., a data storage which iscomprised in the image capturing device, such as data storage 203comprised in smartphone 210 or digital camera 220. The internal datastorage may, e.g., be a built-in memory or a removable memory card,based on Random Access Memory (RAM), Flash memory, or the like.

With reference to FIG. 3, first image capturing device 131 captures 311a first image which is subsequently stored 313 in the first datastorage, which is an internal data storage 203 of first image capturingdevice 131. During capturing 311 of the first image, first imagecapturing device 131 emits a first flash 151 of coded light forilluminating scene 110 which is captured 311 in the first image.Information is encoded into first flash 151 which enables retrieval ofthe first image from the first data storage. For instance, the encodedinformation may comprise an IP address, a URL, any other type of networkaddress, or a device identifier, which enables other network nodes,including further image capturing devices, to access the first datastorage of first image capturing device 131 and retrieve of the firstimage.

As an example, the encoded information may comprise an IP address whichis currently assigned to first image capturing device together with apath which can be resolved by first image capturing device 131 toretrieve the first image if a request for the first image is received:

-   -   172.16.254.1/shared/images/image0123.jpg

In this example, “172.16.254.1” is the IP address which is assigned tofirst image capturing device 131, and “/shared/images/image0123.jpg” isthe path to the first image “image0123.jpg” in the local data storage203. It will be appreciated that embodiments of the invention are notlimited to IPv4-types of addresses exemplified above, but may use anytype of information which is suitable for identifying the location of animage in a data storage.

The encoded information may additionally comprise credentials which arerequired for retrieving the first image from the first data storage,such as a login and/or a password, or a shared secret. It mayadditionally comprise further information, such as informationidentifying a user 121 of first image capturing device 131, e.g., anemail address, a name, an address, a phone number, or a link to a socialnetwork page of user 121. In addition, the information may also compriseother information which is frequently stored as metadata with images,such as a current time stamp for identifying the date and time when thefirst image was captured 311, and/or position or location informationidentifying a position or location of first image capturing device 131when the first image was captured 311. Advantageously, first flash 151may be detected, and the information it carries decoded, by any imagecapturing device 132 or 133 which is in proximity of first imagecapturing device 131, allowing user 121 to share a picture she has takenwith other people 122 and 123 in a simple way.

Substantially coinciding with capturing 311 of the first image by firstimage capturing device 131, second image capturing device 133 captures314 a second image which it stores 315 in a second data storage 203,which in sequence diagram 310 is assumed to be a local data storage 203,i.e., comprised in second image capturing device 133. During capturing314 of the second image, second image capturing device 133 emits asecond flash 153 of coded light. Information is encoded into secondflash 153 which enables retrieval of the second image from the seconddata storage, in accordance with what is described above with referenceto information which is encoded into first flash 151.

First image capturing device 131 detects second flash 153, by means ofits image sensor 201 or a separate sensor which is dedicated for sensingflashes of coded light, and decodes 317 the information which is encodedinto second flash 153. Second flash 153 is an indication that secondimage capturing device 133 has captured the second image. Moreover,detecting second flash 153 by first image capturing device 131 is anassurance that both image capturing devices 131 and 133 have been inproximity when the second image was captured 314 by second imagecapturing device 133, and that first image capturing device 131 had itsimage sensor, having a field of view 141, directed towards the scene 110which was illuminated by second image capturing device 133, as isillustrated in FIG. 1. That is, users 121 and 123, operating first andsecond image capturing devices 131 and 133, respectively, are in theprocess of taking pictures of the same scene 110.

The decoded 317 information may subsequently be used for retrieving thesecond image from the second data storage, where it has been stored bysecond image capturing device 133. For instance, first image capturingdevice 131 may request 318 the second image from second image capturingdevice 133, which retrieves the second image from its local datastorage, the second data storage, and transmits 319 the second image tofirst image capturing device 131. The request 318 for the second imagemay comprise any one, or a combination of, an IP address, URL, a deviceidentifier, or any other type of network address or identifier assignedto second image capturing device 133, in combination with a path to thesecond image in the second data storage, e.g.:

-   -   172.16.254.3/shared/images/image0456.jpg

In this example, “172.16.254.3” is the IP address which is assigned tosecond image capturing device 133, and “/shared/images/image0456.jpg” isthe path to the second image “image0456.jpg” in the local data storage203. It will be appreciated that embodiments of the invention are notlimited to IPv4-types of addresses exemplified above, but may use anytype of information which is suitable for identifying the location of animage in a data storage. The request 318 and its response 319 mayutilize any suitable protocol such as Transmission Control Protocol(TCP)/IP, HyperText Transfer Protocol (HTTP), or the like. The exchangeof messages 318 and 319 is effected by means of wireless communications,utilizing network interfaces 204 which image capturing devices 131 and133 are provided with. The wireless communications may either beeffected directly between first image capturing device 131 and secondcapturing device 133, e.g., using a Wireless Local Area Network(WLAN)/WiFi ad-hoc network, AirPlay, Bluetooth, or the like, or througha communications network 101, such as the Internet, and one or moreRadio Access Networks 102 (RANs).

In response to receiving 319 the second image from second imagecapturing device 133, first image capturing device 131 creates 320 a 3Dmodel from the first image and the second image, using any algorithmknown in the art. Optionally, the 3D model is only created 320 if a timeinterval between capturing 311 the first image and capturing 314 thesecond image is below a threshold time interval. Together with theassurance that the first image and the second image have captured thesame scene, this implies that the first image and the second image aresuitable for creating a 3D model, under the condition that the thresholdtime interval is sufficiently short. The threshold time interval may,e.g., be configured by user 121 of image capturing device 131, and/ordetermined based on the algorithm which is used for creating 320 a 3Dmodel from the first and the second image. Alternatively, the thresholdtime interval may be determined dynamically, based on an amount ofmotion in the captured scene. For instance, the faster an object in thecaptured scene moves, the shorter the threshold time interval. This isparticularly advantageous if a non-static scene is captured.

Advantageously, embodiments of the invention do not rely on time stampsof images which are retrieved from other image capturing devices.Rather, an image capturing device detecting a flash emitted by anotherimage capturing device can establish the time of capture based on itsown internal clock. Thereby, the time which has lapsed between capturing311 the first image and capturing 314 the second image can beestablished with high accuracy.

In addition to the time which has lapsed between capturing 311 the firstimage and capturing 314 the second image, other criteria may be used forassessing the suitability of the first image and the second image forcreating 320 a 3D model, such as the brightness of the second image.That is, if the second image is sufficiently bright, this is anindication that the second image captures the scene which wasilluminated by first flash 151.

Optionally, the second image is only retrieved 318/319 if the timeinterval is below the threshold time interval, and/or if it is assessedthat the first image and the second image are suitable for creating 320a 3D model. Thereby, images are only retrieved if it is likely that theyare suitable for creating a 3D model.

As an alternative to retrieving 318/319 the second image from secondimage capturing device 133 and creating 320 a 3D model from the firstand the second image, first image capturing device 131 may, afterdecoding 317 the information which is encoded into second flash 153,associatively store the decoded information with the first image (notillustrated in FIG. 3), e.g., as metadata of the first image or in adatabase where it is stored together with information identifying thefirst image, such as a filename or an identifier of the first image.

As an example, if the first image is stored in a local data storage 203of first image capturing device 131 in a file “image0123.jpg”, and thesecond image can be accessed at a location in a local data storage ofsecond image capturing device 153, e.g.,“172.16.254.3/shared/images/image0456.jpg”, the following entry may bestored in the database:

image0123.jpg; 172.16.254.3/shared/images/image0456.jpg

The associatively stored information can subsequently be used forcreating a 3D model from the first and the second image, by retrievingthe first image, retrieving the second image, and algorithmicallycombining the first and the second image into a 3D model using one ofthe algorithms known in the art.

Further with reference to FIG. 3, sequence diagram 330 is similar tosequence diagram 310 but illustrates an alternative embodiment of theinvention. Here, image capturing device 131 captures 311 the first imagein response to detecting second flash 153 emitted by second imagecapturing device 133. In other words, second flash 153 triggerscapturing 311 of the first image. In this way, it can be ensured thatthe first image and the second image are captured 311/314 within acertain (relatively short) time interval. For instance, first imagecapturing device 131 may be configured, e.g. by user 121, to capture thefirst image in response to detecting a flash emitted by another imagecapturing device. Together with the assurance that the first image andthe second image capture the same scene, this implies that the firstimage and the second image are suitable for creating 320 a 3D model,under the condition that the time interval is configured to besufficiently short to allow creation 320 of a 3D model. Moreover, ifseveral image capturing devices are set to capture an image in responseto detecting a flash emitted by another image capturing device, a set of2D images can be captured within a time interval which is sufficientlyshort to allow creation of a 3D model.

In FIG. 4, a further sequence diagram 410 is shown which illustratesembodiments of the invention utilizing an external data storage, such asa server or a network node 103 for exchanging and/or sharing capturedimages. External data storage 103 is accessible by first image capturingdevice 131 and second image capturing device 133, typically via acommunications network 101, e.g., the Internet, and/or one or more RANs102. The steps and message exchanges illustrated in sequence diagram 410are similar to those described with reference to FIG. 3, with theexception of second image capturing device 133 storing 415 the secondimage in external data storage 103, instead of an internal data storage203, and first image capturing device 131 retrieving 418/419 the secondimage from external data storage 103. Storing 415 the second image isachieved by transmitting 415 the second image to external data storage103, and retrieving the second image is achieved by requesting 418 thesecond image from external data storage 103, which in response toreceiving request 418 transmits 419 the second image to first imagecapturing device 131. The request 418 and its response 419 may utilizeany suitable protocol such as TCP/IP, HTTP, or the like. The exchange ofmessages 418 and 419 is effected by means of wireless communications,utilizing network interfaces 204 which image capturing devices 131 and133 are provided with.

It will also be appreciated that first image capturing device 131 andsecond image capturing device 133 may effect wireless communicationsdirectly with external data storage 103, if external data storage 103 isprovided with a compatible network interface. For instance, externaldata storage 103 may be a data storage device which is set up forcollecting images at an event, such as a Network Attached Storage (NAS)which is configured for communicating with image capturing devices131-133 via WLAN/WiFi, Bluetooth, AirPlay, an ad-hoc network, or thelike.

Embodiments of the invention may utilize an external data storage 103which is operated by a social network or a provider of an image sharingservice, e.g., Facebook or Instagram. In such case, the informationenabling retrieval of an image from external data storage 103 may, e.g.,comprise a URL of a social network page of a user of the image capturingdevice, or a page for posting images, in combination with a pathidentifying the location of the image. As an example, the informationmay be of the form:

http://facebook.com/userABC/images/image0456.jpg

In this example, the information identifies the location of image“image0456.jpg” on a Facebook page of user “userABC”. As a furtherexample, the URL may comprise an identifier of the image, which can beused for retrieving the image from a database:

http://facebook.com/photo.php?fbid=12345678912345,

where “12345678912345” identifies a certain image, e.g., “image0456.jpg”of user “userABC”.

Embodiments of the invention utilizing external data storage 103 mayalso be envisaged which capture 311 the first image in response todetecting second flash 153, in correspondence to what is illustrated insequence diagram 330 show in FIG. 3.

It will also be appreciated that embodiments of the invention are notlimited to the exact order of steps performed by image capturing devices131 and 133, and the order of messages exchanged between them, asillustrated in sequence diagrams 310, 330, and 410. For instance, firstimage capturing device 131 may store 313/413 the first image beforedecoding 317/417 the information which is encoded into second flash 153.

By encoding information into a flash, using visible coded light, whichinformation enables retrieval of an image captured by an image capturingdevice, embodiments of the invention provide an easy way of sharing animage with other people who were present, and operating their respectiveimage capturing devices, when the image was captured. The solutionprovided herein alleviates participants at an event, such as a wedding,a birthday party, or the like, from exchanging contact information orotherwise engage in the process of sharing their images with each other.Rather, the information which enables retrieval of a captured image canbe obtained by detecting a flash which is emitted by an image capturingdevice capturing an image. In that way, images can be shared with othersin an easy manner, regardless of whether they are subsequently used forcreating a 3D model from a set of suitable 2D images, or for otherpurposes. In particular, embodiments of the invention may advantageouslybe used for the sole purpose of sharing images.

It will also be appreciated that embodiments of the invention are notlimited to sharing of images between only two image capturing devices,such as first image capturing device 131 and second image capturingdevice 133. Rather, embodiments of the invention may be envisaged whichshare images with, and/or retrieve images from, any number of otherimage capturing devices. Advantageously, an improved 3D model isobtained if more than two 2D images are used for creating the 3D model.

In the following, embodiments of image capturing devices 131-133 aredescribed with reference to FIG. 2, which illustrates a smartphone 210and a digital camera 220. An embodiment 210/220 of the image capturingdevice comprises an image sensor 201 for capturing a first image of ascene 110, a light source 202 for illuminating the scene with a firstflash 151 of coded light during capturing of the first image by imagesensor 201, and a network interface 204 for effecting wirelesscommunications with a RAN 102 and/or a further image capturing device.

In the present context, an image sensor may, e.g., be of Charge CoupledDevice (CCD) or Complementary Metal-Oxide-Semiconductor (CMOS) type, andis used for converting light into discrete signals which can be storedin digital format and processed by digital electronics, e.g., aprocessor. Typically, modern smartphones 210 comprise at least one imagesensor 201 which is provided on the rear face. It will be appreciatedthat such image sensors are frequently combined with an optical system,such as a lens, to focus the light on the image sensor, a shutter, andthe like. Alternatively, the image sensor may also be of light-fieldcamera type, which allows post-capture change of focal depth.

Light source 202 may, e.g., be a Light-Emitting Diode (LED) which isfrequently used as flash in today's smartphones 210. Due to the highswitching frequency of LEDs, LED-based flashes are particularly suitablefor encoding information into flashes of light, as is described herein.Alternatively, Xenon-type flashes may be used as light source 202.

Network interface 204 may support wireless communications via a cellularmobile network, e.g., Global System for Mobile Communications (GSM),Universal Mobile Telecommunications System (UMTS), or Long TermEvolution (LTE), via a WLAN/WiFi network, or utilize a short-rangedradio technology such as Bluetooth.

Image capturing device 210/220 further comprises processing means 205which are operative to encode information into the first flash, whichinformation enables retrieval of the first image from a first datastorage, capture the first image, and store the first image in the firstdata storage. The first data storage may either be comprised in theimage capturing device, such as built-in data storage 203, or externaldata storage 103 which is accessible via communications network 101and/or RAN 102. The information which is encoded into the first flashmay comprise a location of the first image in the first data storage,such as an IP address, and URL, a path, or the like, and may furthercomprise additional information described hereinbefore.

In an embodiment of image capturing device 2110/220, image sensor 201 isfurther operative to detect a second flash of coded light emitted by afurther image capturing device, and processing means 205 is furtheroperative to decode information which is encoded into the second flash,which information enables retrieval of a second image captured by thefurther image capturing device from a second data storage, retrieve thesecond image from the second data storage, and create a 3D model fromthe first image and the second image. The second data storage may becomprised in the further image capturing device, such as built-in datastorage 203, or external data storage 103 which is accessible viacommunications network 101 and/or RAN 102. The second image is retrievedvia network interface 204, either directly from the further imagingcapturing device, e.g., via short-ranged radio or an ad-hoc WLAN/WiFinetwork, or from external data storage 103, e.g., a network node orserver which is accessible via communications network 101 and/or RAN102. Optionally, the 3D model is only created if a time interval betweencapturing the first image and capturing the second image is below athreshold time interval. Further optionally, the second image is onlyretrieved if the time interval is below the threshold time interval,and/or if other criteria are fulfilled, e.g., if the brightness of thesecond image exceeds a certain threshold value, as was described before.

As an alternative to retrieving the second image based on theinformation which is encoded into the second flash, embodiments of imagecapturing device 210/220 may also decode the information which isencoded into the second flash and associate the decoded information withthe first image. In particular, this may be achieved by associativelystoring the information with the first image, either as metadata of thefirst image or in a database, as was described hereinbefore.

Optionally, embodiments of image capturing device 210/220 may capturethe first image in response to detecting the second flash emitted by thefurther image capturing device. That is, the second flash triggerscapturing of the first image. For instance, an embodiment of imagecapturing device 210/220 may be configurable, by means of user settings,to capture an image when the camera button is pressed down and when aflash is detected. Thereby, if several image capturing devices are usedfor capturing 2D images of the same scene, the image capturing devicecapturing the first image may trigger capturing of images by the otherimage capturing devices. Advantageously, a set of images is therebyobtained which are captured within a relatively short time interval, andwhich accordingly are suitable for creating a 3D model of the capturedscene.

In FIG. 5, two embodiments 510 and 520 of processing means 205,comprised in image capturing device 210/220, are shown.

Processing means 510 comprises a processing unit 511, such as a generalpurpose processor, and a computer-readable storage medium 512, such as aRAM, a Flash memory, or the like. In addition, processing means 510comprises one or more interfaces 515 (“I/O” in FIG. 5) for controlling,and receiving information from, image sensor 201, light source 202,internal data storage 203, and network interface 204.

Memory 512 contains computer-executable instructions 513, i.e., acomputer program, for causing an image capturing device, such as asmartphone, a digital camera, a mobile terminal, a UE, a tablet, or thelike, to perform in accordance with an embodiment of the invention asdescribed herein, when computer-executable instructions 513 are executedon processing unit 511.

In an alternative embodiment, processing means 520 comprises acoded-light module 521 for encoding information into the first flash ofcoded light, a capturing module 522 for capturing a first image of ascene, a data storage module 523 for storing the first image in a firstdata storage, and an optional 3D model module 524 for creating a 3Dmodel from the first image and a second image which is retrieved from afurther image capturing device. In addition, processing means 520comprises one or more interfaces 525 (“I/O” in FIG. 5) for controlling,and receiving information from, image sensor 201, light source 202,internal data storage 203, and network interface 204. Modules 521-525may be implemented by any kind of electronic circuitry, e.g., any one,or a combination of, analogue electronic circuitry, digital electroniccircuitry, and processing means executing a suitable computer program.

In FIG. 6, a flow chart 600 is shown which illustrates embodiments ofthe method of an image capturing device, such as a smartphone, a digitalcamera, a mobile terminal, a UE, a tablet, or the like. Method 600comprises illuminating 602 a scene with a first flash of coded light,wherein information is encoded 601 into the first flash, capturing 603 afirst image of the scene, and storing 604 the first image in a firstdata storage. The information which is encoded 601 into the first flashenables retrieval of the first image from the first data storage. Thefirst data storage may, e.g., be comprised in the image capturingdevice. Alternatively, the first data storage may be an external datastorage which is accessible by the image capturing device, and the firstimage is stored in the first data storage by transmitting the firstimage to the first data storage. The information which is encoded intothe first flash may, e.g., comprise a location of the first image in thefirst data storage.

Method 600 may further comprise detecting 605 a second flash of codedlight emitted by a further image capturing device, and decoding 606information which is encoded into the second flash. The encodedinformation enables retrieval of a second image captured by the furtherimage capturing device from a second data storage. The second datastorage may, e.g., be comprised in the further image capturing device.Alternatively, the second data storage may be an external data storagewhich is accessible by the further image capturing device. Theinformation which is encoded into the second flash may, e.g., comprise alocation of the second image in the second data storage. Method 600 mayfurther comprise retrieving 607 the second image from the second datastorage, and creating 608 a 3D model from the first image and the secondimage. Optionally, the 3D model is only created 608 if a time intervalbetween capturing the first image and capturing the second image isbelow a threshold time interval.

As an alternative to retrieving 607 the second image and creating 608 a3D model, the decoded information may also be associatively stored 609with the first image, as metadata of the first image or in a database,as is described hereinbefore.

The first image may optionally be captured in response to detecting thesecond flash emitted by the further image capturing device, as isillustrated in sequence diagram 330 shown in FIG. 3 and describedhereinbefore.

It will be appreciated that method 600 may comprise additional, ormodified, steps in accordance with what is described throughout thisdisclosure. An embodiment of method 600 may be implemented as software,such as computer program 513, to be executed by a processing unitcomprised in an image capturing device, such as processor 511 describedwith reference to FIG. 5, whereby the image capturing device isoperative to perform in accordance with embodiments of the inventiondescribed herein.

The person skilled in the art realizes that the invention by no means islimited to the embodiments described above. On the contrary, manymodifications and variations are possible within the scope of theappended claims.

1. An image capturing device comprising: an image sensor for capturing afirst image of a scene; a light source for illuminating the scene with afirst flash of coded light during capturing of the first image by theimage sensor; a network interface for effecting wireless communicationswith one or more of a communications network and a further imagecapturing device, the image sensor being operative to detect a secondflash of coded light emitted by the further image capturing device; anda processing unit being operative to: encode information into the firstflash during capturing of the first image by the image sensor, theinformation enabling retrieval of the first image from a first datastorage, capture the first image; store the first image in the firstdata storage; decode information which is encoded into the second flash,the information enabling retrieval of a second image captured by thefurther image capturing device from a second data storage; retrieve thesecond image from the second data storage; and create a 3D model fromthe first image and the second image, wherein the first image iscaptured in response to detecting the second flash emitted by thefurther image capturing device.
 2. The image capturing device accordingto claim 1, wherein the 3D model is only created if a time intervalbetween capturing the first image and capturing the second image isbelow a threshold time interval.
 3. The image capturing device accordingto claim 1, the image sensor being operative to detect a second flash ofcoded light emitted by the further image capturing device, theprocessing unit being further operative to: decode information which isencoded into the second flash, the information enabling retrieval of asecond image captured by the further image capturing device from asecond data storage; and associatively store the decoded informationwith the first image.
 4. The image capturing device according to claim1, wherein the encoded information comprises a location of an image in adata storage.
 5. The image capturing device according to claim 1,wherein the first data storage is comprised in the image capturingdevice.
 6. The image capturing device according to claim 1, wherein thefirst data storage is an external data storage which is accessible overthe communications network, and the first image is stored in the firstdata storage by transmitting the first image via the network interfaceto the first data storage.
 7. The image capturing device according toclaim 1, wherein the second data storage is comprised in the furtherimage capturing device.
 8. The image capturing device according to claim1, wherein the second data storage is an external data storage which isaccessible over the communications network.
 9. The image capturingdevice according to claim 1, wherein the image capturing device is amobile terminal, a smartphone, a User Equipment, a tablet, or a digitalcamera.
 10. A method of an image capturing device, the methodcomprising: illuminating a scene with a first flash of coded lightduring capturing of a first image; capturing the first image of thescene; and storing the first image in a first data storage, whereininformation is encoded into the first flash, the information enablingretrieval of the first image from the first data storage; detecting asecond flash of coded light emitted by a further image capturing device;decoding information which is encoded into the second flash, theinformation enabling retrieval of a second image captured by the furtherimage capturing device from a second data storage; retrieving the secondimage from the second data storage; and creating a 3D model from thefirst image and the second image, wherein the first image is captured inresponse to detecting the second flash emitted by the further imagecapturing device.
 11. The method according to claim 10, wherein the 3Dmodel is only created if a time interval between capturing the firstimage and capturing the second image is below a threshold time interval.12. The method according to claim 10, further comprising: detecting asecond flash of coded light emitted by a further image capturing device;decoding information which is encoded into the second flash, theinformation enabling retrieval of a second image captured by the furtherimage capturing device from a second data storage; and associativelystoring the decoded information with the first image.
 13. The methodaccording to claim 10, wherein the encoded information comprises alocation of an image in a data storage.
 14. The method according toclaim 10, wherein the first data storage is comprised in the imagecapturing device.
 15. The method according to claim 10, wherein thefirst data storage is an external data storage which is accessible bythe image capturing device, and the first image is stored in the firstdata storage by transmitting the first image to the first data storage.16. The method according to claim 10, wherein the second data storage iscomprised in the further image capturing device.
 17. The methodaccording to claim 10, wherein the second data storage is an externaldata storage which is accessible by the image capturing device.
 18. Themethod according to claim 10, wherein the image capturing device is amobile terminal, a smartphone, a User Equipment, a tablet, or a digitalcamera.
 19. A computer program comprising computer-executableinstructions for causing a device to perform the method according toclaim 10, when the computer-executable instructions are executed on aprocessing unit comprised in the device.
 20. A computer program productcomprising a non-transitory computer-readable storage medium, thecomputer-readable storage medium having the computer program accordingto claim 19 embodied therein.